Taking Steps for Cleaner Air for Respiratory Virus Prevention

What to know
  • Taking steps for cleaner air is a core prevention strategy to lower risk from respiratory viruses.
  • Core prevention strategies are important steps you can take to protect yourself and others from respiratory viruses.


picture of a person opening a window

Steps for cleaner air‎

Take steps for cleaner air. This can mean bringing in fresh outside air, purifying indoor air, or gathering outdoors. Virus particles do not build up in the air outdoors as much as they do indoors.

How it works

Some germs spread in the air between people. This happens more easily in indoor, crowded spaces with poor airflow. To reduce the risk of exposure, it helps to improve air quality by increasing airflow, cleaning the air, or opting to gather outdoors.

Steps you can take

Individuals can

  • Bring as much fresh air into your home as possible by opening doors and windows and/or using exhaust fans.
  • If your home has a central heating, ventilation, and air conditioning system (HVAC, a system with air ducts that go throughout the home) that has a filter, set the fan to the “on” position instead of “auto” when you have visitors and use pleated filters. Change your filter every three months or according to the manufacturer’s instructions.
  • Use a portable high-efficiency particulate air (HEPA) cleaner.
  • Move activities outdoors, where airflow is best.
  • Use CDC’s Interactive Home Ventilation Tool to see how particle levels change as you adjust ventilation settings.

Organizations can

  • Ensure existing HVAC systems are providing at least the minimum outdoor air ventilation requirement in accordance with ventilation design codes. Applicable codes are based on the year of building construction or latest renovation and intended building occupancy.
  • Aim for 5 or more air changes per hour (ACH) of clean air. This can be achieved through any combination of central ventilation system, natural ventilation, or additional devices that provide equivalent ACH to your existing ventilation.

Key times for prevention

All of the prevention strategies described in this guidance can be helpful to reduce risk. They are especially helpful when:


CDC offers separate, specific guidance for healthcare settings (COVID-19, flu, and general infection prevention and control). Federal civil rights laws may require reasonable modifications or reasonable accommodations in various circumstances. Nothing in this guidance is intended to detract from or supersede those laws.